Adaptor boxes are used for mounting low voltage lighting fixtures to a low voltage track. As well recognized, such adaptor boxes must not only provide reliable mechanical support for the lighting fixture but also reliable electrical connection. As such fixtures typically operate on only 12 volts, even a small voltage drop at the connection to the track may result in a discernable effect on the operation of the light fixture.
At the same time the adaptor boxes should be of desirably small size with few parts, affording economic manufacture and assembly at high volume.
U.S. Pat. No. 6,059,582 issued May 9, 2000 to the present inventor Tsai, the disclosure of which is incorporated herein by reference, teaches a commercially successful adaptor box for mounting a fixture to a conventional low voltage lighting track comprising an insulating body formed by an elongate web joining flanges, having respective free ends from which mounting edge portions protrude inwards towards each other over the elongate web defining a channel section cavity for receiving a mounting head portion of the adapter box, ears located adjacent junctions of the flanges and the web and wire busses mounted on respective ears.
The adaptor box comprises a housing molded in one piece of insulating plastic material and comprising opposite side walls joined by upper, lower and rear walls providing a housing cavity having a front which is open, a mounting head integrally formed with the upper wall to upstand therefrom and formed with opposed mounting ears and a contact receiving through-passageway having a front, contact insertion opening, both the contact receiving through-passageway and the front, contact insertion opening extend from the housing cavity vertically through the mounting head between the mounting ears, the upper wall being formed with a recess extending from the front of the housing cavity which is open to the front, contact insertion opening so that the housing is open at a front and at a top, from the front to the front, contact insertion opening; an opening in the lower wall; an insert molded in one piece of insulating plastic material comprising a contact separating rib and a releasable, rotation preventing latching tab portion connected together to extend in generally parallel relation, one above the other, by a transverse, resilient web hinge; a pair of contacts extending through the contact receiving through-passageway each having one end for connection to respective conductors of a fixture and another end exposed for electrical connection to respective track busses; means for attaching a low voltage lighting fixture to the housing, and the housing and the insert having resilient latching means cooperable to assemble the housing and insert together in a snap fit; the insert being assembled with the housing by insertion of the contact separating rib through the front, contact insertion opening into the through-passageway, between the contacts, with the rotation preventing latching tab portion extending across the front of the housing cavity and the transverse, resilient web hinge extending across the recess, the rotation preventing latching tab comprising an upper catch portion which, in an undeformed position of the resilient web hinge, protrudes above the upper wall of the housing in a rotation preventing position preventing rotation of the housing relative to the channel section cavity of the track when the mounting head is received therein and a lower fingerpiece, depressible to deform the resilient web hinge and withdraw the upper catch portion toward the upper wall to a release position permitting rotation of the mounting head within the channel section cavity of the track to enable removal of the adaptor box therefrom.
In the adaptor box described above, the contacts are terminated to respective wires of a fixture by soldering or crimping thereto, establishing permanent connections with the fixture wires, and the contacts and wires subsequently threaded into the adaptor housing and positioned accurately in the contact receiving passageway of the mounting head and the insert subsequently assembled with the housing. The assembled adaptor box can then be mounted to the low voltage track.
A disadvantage of such arrangement is that changing the fixture requires disassembly of the adaptor box demounted from the track. The need to assemble and disassemble the adaptor box demounted from the track prevent a fixture being mounted to the track as rapidly as may be desired in some circumstances.